Project Summary/Abstract The United States is in the midst of an opioid epidemic. In 2016 (most recent estimates), 2.1 million people met diagnostic criteria for opioid use disorder (OUD). In that same year, 42,249 Americans died of opioid overdose?an average of 116 preventable deaths per day. Opioid agonist therapy (OAT), such as buprenorphine/naloxone (BUP/NAL), can reduce opioid overdose deaths by at least 70%, decrease opioid misuse, and improve quality of life. Because of its proven efficacy, the National Institute on Drug Abuse (NIDA), the Substance Abuse and Mental Health Services Administration (SAMHSA), the American Society of Addiction Medicine (ASAM), and the American Academy of Addiction Psychiatry (AAAP) endorse the use of medication-assisted therapy in the treatment of OUD. Poor medication adherence is one of the main barriers to long term efficacy of OAT. Our aim is to substantially increase adherence to oral BUP/NAL with Pillsy, a smart technology platform developed over the past 3 years using principles of behavioral science, modern design, and highly scalable wireless and mobile technologies. Pillsy acts like a digital medication coach, providing education and reminders using a mobile app, text messages, and automated phone calls. The platform is built around a Bluetooth-based smart pill bottle cap that automatically tracks doses, timing and sends intelligent reminders to create a unique feedback loop, which allows us to constantly optimize our incentive/reminder messages to meet user needs to increase adherence. A dashboard enables providers to easily medication use and patient engagement. Pillsy can substantially increase adherence to OAT and decrease opioid-related morbidity and mortality. Since Pillsy only nominally increases the cost of oral BUP/NAL treatment and physicians can bill for monitoring time (CPT code 99091), it is an attractive solution to patients, physicians, and payers. In Phase I of the Fast Track project, we conduct qualitative interviews with OUD patients and providers that will guide the development of patient-tailored messages and a physician-specific dashboard. We will build out and adapt our current Pillsy platform, then test it in small-scale trial to assess feasibility, usability, and efficacy. Using the data obtained in Phase I and after meeting with the FDA, we will further refine the platform in Phase II. Once complete, we will perform a randomized efficacy trial in at least 200 patients with OUD. At the end of this trial we will demonstrate that Pillsy significantly improves adherence to BUP/NAL compared to service as usual as determined by mediation possession ratio, in-office urine drug screening, and patient self- report. Secondarily, we will show Pillsy decreases non-prescribed opioid use and significantly increases treatment retention. These results will be submitted to the FDA and will serve as the basis for broader commercialization/marketing of Pillsy in the opioid use disorder/Medication-Assisted Treatment space.